<VV> Re: l Fox <paulvair@yahoo.com> Subject: Re Octane/Ping

FrankCB at aol.com FrankCB at aol.com
Sun Jun 26 21:05:56 EDT 2005


Padgett,
       Electric fans simply take too much power for too long a time period.  
You can safely take 150 amps or even more from the Corvair's electrical system 
for brief periods (like starting the engine) but you'll overwhelm the 35 amp 
charging system if you do it for longer periods.
       Instead of trying to vary the speed of the fan with a variable speed 
drive, you might consider trying to restrict the flow of air through the 
engine.  Since the fan's power drain depends on the amount of air being moved, 
anything you can do to restrict the flow of air at the same fan speed will reduce 
the power the fan consumes. Just make sure you have good CHT indication and 
control since the air cooled engine can overheat rather quickly.
       I think 3.08 gears are GREAT for highway cruising.  The problem with 
the usual Corvair 3.55 gearing is that it gives you about 3000 rpm at 60 mph.  
With 3.08 gears this would be reduced to around 2600 rpm which, while not a 
big reduction, is a move in the right direction.  My 95 Trans Port minivan turns 
only 1800 rpm at 60 mph.  This is why it gets better mileage than a Corvair 
that weighs 1/3 less and has an engine about 30% smaller in displacement.  Of 
course without the precision of computer control and port fuel injection, the 
Corvair engine wouldn't be too responsive at 1800 rpm.  But, on the other hand, 
I remember back in the 70s driving to Lime Rock late one night right after 
one of the 140's mufflers had fallen off.  Since we didn't want to attract the 
attention of the local constabulary (aka cops) of the small towns we were 
driving through and risk getting a ticket, I kept the rpm considerably below 2000 
rpm and maintained a VERY light touch on the accelerator pedal with frequent 
shifting to minimize the noise.  Fortunately the primary carbs were running well 
so we could get away with this and made the rest of the trip without 
problems.
       Regards,
       Frank "light footed" Burkhard 

In a message dated 6/23/05 5:52:18 PM Eastern Daylight Time, pp2 at 6007.us 
writes:

> I also have to wonder just how much hp is used for the fan at a 70 mph/3500 
> 
> rpm cruise (either electrics of a CVT drive would allow constant fan flow: 
> with a bit of reprogramming, my computer cars run 181-185F even in hot for 
> Orlando weather.
> 
> Just as an aside, are 3.08 gearsets considered valuable for anything ? 
> Since a big hunk of the cooling issue is IHP losses, keeping the revs low 
> can really help (odd thing is that back at GMI, people thought I was crazy 
> promoting very steep axle ratios for low rpm cruise but as far as I was 
> concerned it was a win-win situation. My test bed then was a 327-275 hp 
> Camaro (because I had it) with a 4-speed and Rochester FI. using very tall 
> tires (H78-15) to keep the revs down on Interstates. Could of gone furter 
> but never found a B-W o/d to mate with a Saginaw 4-speed.
> 
> Padgett 
> 



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